Platoon (automobile)

Grouping vehicles into platoons is a method of increasing the capacity of roads. An automated highway system is a proposed technology for doing this.

Platoons decrease the distances between cars using electronic, and possibly mechanical, coupling. This capability would allow many cars to accelerate or brake simultaneously. Instead of waiting after a traffic light changes to green for drivers ahead to react, a synchronized platoon would move as one, allowing up to a fivefold increase in traffic throughput if spacing is diminished that much. This system also allows for a closer headway between vehicles by eliminating reacting distance needed for human reaction.

Platoon capability might require buying new cars, or it may be something that can be retrofitted. Drivers would probably need a special license endorsement on account of the new skills required and the added responsibility when driving in the lead.

Smart cars with artificial intelligence could automatically join and leave platoons. The automated highway system is a proposal for one such system, where cars organise themselves into platoons of eight to twenty-five.

Potential benefits

• Greater fuel economy due to reduced air resistance.
• Reduced congestion
• Substantially shorter commutes during peak periods.
• On longer highway trips, vehicles could be mostly unattended whilst in following mode.
• Fewer traffic collisions

Potential downsides

• Drivers would feel less in control of their own driving, being at the hands of computer software, or the lead driver

Automated highway system

An automated highway system (AHS) or Smart Road is a proposed intelligent transportation system technology designed to provide for driverless cars on specific rights-of-way. It is most often touted as a means of traffic congestion relief, as it would drastically reduce following distances and headway, thus allowing more cars to occupy a given stretch of road.

How it works

In one scheme, the roadway has magnetized stainless-steel spikes driven one meter apart in its center. The car senses the spikes to measure its speed and locate the center of the lane. Furthermore, the spikes can have either magnetic north or magnetic south facing up. The roadway thus provides small amounts of digital data describing interchanges, recommended speeds, etc.

The cars have power steering and automatic speed controls, which are controlled by a computer.

The cars organize themselves into platoons of eight to twenty-five cars. The platoons drive themselves a meter apart, so that air resistance is minimized. The distance between platoons is the conventional braking distance. If anything goes wrong, the maximum number of harmed cars should be one platoon.

Early development

The origin of research on AHS was done by a team from The Ohio State University led by Dr. Robert E. Fenton. Their first automated vehicle was built in 1962, and is believed to be the first land vehicle to contain a computer. Steering, braking and speed were controlled through the onboard electronics, which filled the trunk, back seat and most of the front of the passenger side of the car. Research continued at OSU until federal funding was cut in the early 1980s.

Deployments

The PATH project, a prototype automated highway system, was tested in San Diego County, California in 1991 along Interstate 15. However, despite the technical success of the program, investment has moved more toward autonomous intelligent vehicles rather than building specialized infrastructure. The AHS system places sensory technology in cars that can read passive road markings, and use radar and inter-car communications to make the cars organize themselves without the intervention of drivers. Such an autonomous cruise control system is being developed by Mercedes-Benz, BMW, Volkswagen and Toyota.

The SARTRE Project (Safe Road Trains for the Environment), is a European Commission funded project investigating implementation of platooning on unmodified European motorways. Begun in September 2009, the three year project successfully trialled a two vehicle platoon in January 2011.

See also

• Driverless car
• Future of the car
• Green wave
• Vehicle Infrastructure Integration
• Virginia Smart Road

External links

• Roadtrains.US
• Vehicle Platooning and Automated Highways Description of the San Diego experiment.
• Underground Automated Highway Systems Forecast for the future of urban transportation.
• Safe Road Trains for the Enivironment